Publications

Order by: publication date number of citations

• EXCESS workshop: Descriptions of rising low-energy spectra

  P. Adari, A. Aguilar-Arevalo, D. Amidei, G. Angloher, E. Armengaud, C. Augier, L. Balogh, S. Banik, D. Baxter, C. Beaufort, G. Beaulieu, V. Belov, Y. Ben Gal, G. Benato, A. Benoît, A. Bento, L. Bergé, A. Bertolini, R. Bhattacharyya, J. Billard, I.M. Bloch, A. Botti, R. Breier, G. Bres, J-.L. Bret, A. Broniatowski, A. Brossard, C. Bucci, R. Bunker, M. Cababie, M. Calvo, P. Camus, G. Cancelo, L. Canonica, F. Cappella, L. Cardani, J.-F. Caron, N. Casali, G.del Castello, A. Cazes, R. Cerulli, B.A. Cervantes Vergara, D. Chaize, M. Chapellier, L. Chaplinsky, F. Charlieux, M. Chaudhuri, A.E. Chavarria, G. Chemin, R. Chen, H. Chen, F. Chierchie, I. Colantoni, J. Colas, J. Cooley, J.-M. Coquillat, E.C. Corcoran, S. Crawford, M. Crisler, A. Cruciani, P. Cushman, A. D'Addabbo, J.C. D'Olivo, A. Dastgheibi-Fard, M. De Jésus, Y. Deng, J.B. Dent, E.L. Depaoli, K. Dering, S. Dharani, S. Di Lorenzo, A. Drlica-Wagner, L. Dumoulin, D. Durnford, B. Dutta, L. Einfalt, A. Erb, A. Erhart, R. Essig, J. Estrada, E. Etzion, O. Exshaw, F. Favela-Perez, F. v. Feilitzsch, G. Fernandez Moroni, N. Ferreiro Iachellini, S. Ferriol, S. Fichtinger, E. Figueroa-Feliciano, J.-B. Filippini, D. Filosofov, J. A. Formaggio, M. Friedl, S. Fuard, D. Fuchs, A. Fuss, R. Gaïor, A. Garai, C. Garrah, J. Gascon , G. Gerbier, M. Ghaith, V.M. Ghete, D. Gift, I. Giomataris, G. Giroux, A. Giuliani, P. Gorel, P. Gorla, C. Goupy, J. Goupy, C. Goy, M. Gros, P. Gros, Y. Guardincerri, C. Guerin, V. Guidi, O. Guillaudin, S. Gupta, E. Guy, P. Harrington, D. Hauff, S. T. Heine, S. A. Hertel, S.E. Holland, Z. Hong, E.W. Hoppe, T.W. Hossbach, J.-C. Ianigro, V. Iyer, A. Jastram, M. Ješkovský, Y. Jin, J. Jochum, J. P. Johnston, A. Juillard, D. Karaivanov, V. Kashyap, I. Katsioulas, S. Kazarcev, M. Kaznacheeva, F. Kelly, B. Kilminster, A. Kinast, L. Klinkenberg, H. Kluck, P. Knights, Y. Korn, H. Kraus, B. von Krosigk, A. Kubik, N.A. Kurinsky, J. Lamblin, A. Langenkämper, S. Langrock, T. Lasserre, H. Lattaud, P. Lautridou, I. Lawson, S.J. Lee, M. Lee, A. Letessier-Selvon, D. Lhuillier, M. Li, Y.-T. Lin, A. Lubashevskiy, R. Mahapatra, S. Maludze, M. Mancuso, I. Manthos, L. Marini, S. Marnieros, R.D. Martin, A. Matalon, J. Matthews, B. Mauri, D. W. Mayer, A. Mazzolari, E. Mazzucato, H. Meyer zu Theenhausen, E. Michielin, J. Minet, N. Mirabolfathi, K. v. Mirbach, D. Misiak, P. Mitra, J-.L. Mocellin, B. Mohanty, V. Mokina, J.-P. Mols, A. Monfardini, F. Mounier, S. Munagavalasa, J.-F. Muraz, X.-F. Navick, T. Neep, H. Neog, H. Neyrial, K. Nikolopoulos, A. Nilima, C. Nones, V. Novati, P. O'Brien, L. Oberauer, E. Olivieri, M. Olmi, A. Onillon, C. Oriol, A. Orly, J.L. Orrell, T. Ortmann, C.T. Overman, C. Pagliarone, V. Palušová, P. Pari, P. K. Patel, L. Pattavina, F. Petricca, A. Piers, H. D. Pinckney, M.-C. Piro, M. Platt, D. Poda, D. Ponomarev, W. Potzel, P. Povinec, F. Pröbst, P. Privitera, F. Pucci, K. Ramanathan, J.-S. Real, T. Redon, F. Reindl, R. Ren, A. Robert, J.Da Rocha, D. Rodrigues, R. Rogly, J. Rothe, N. Rowe, S. Rozov, I. Rozova, T. Saab, N. Saffold, T. Salagnac, J. Sander, V. Sanglard, D. Santos, Y. Sarkis, V. Savu, G. Savvidis, I. Savvidis, S. Schönert, K. Schäffner, N. Schermer, J. Schieck, B. Schmidt, D. Schmiedmayer, C. Schwertner, L. Scola, M. Settimo, Ye. Shevchik, V. Sibille, I. Sidelnik, A. Singal, R. Smida, M. Sofo Haro, T. Soldner, J. Stachurska, M. Stahlberg, L. Stefanazzi, L. Stodolsky, C. Strandhagen, R. Strauss, A. Stutz, R. Thomas, A. Thompson, J. Tiffenberg, C. Tomei, M. Traina, S. Uemura, I. Usherov, L. Vagneron, W. Van De Pontseele, F.A. Vazquez de Sola Fernandez, M. Vidal, M. Vignati, A.L. Virto, M. Vivier, T. Volansky, V. Wagner, F. Wagner, J. Walker, R. Ward, S.L. Watkins, A. Wex, M. Willers, M.J. Wilson, L. Winslow, E. Yakushev, T.-T. Yu, M. Zampaolo, A. Zaytsev, V. Zema, D. Zinatulina, A. Zolotarova

  SciPost Phys. Proc. 9, 001 (2022) · published 9 August 2022 | Toggle abstract · pdf

  Many low-threshold experiments observe sharply rising event rates of yet unknown origins below a few hundred eV, and larger than expected from known backgrounds. Due to the significant impact of this excess on the dark matter or neutrino sensitivity of these experiments, a collective effort has been started to share the knowledge about the individual observations. For this, the EXCESS Workshop was initiated. In its first iteration in June 2021, ten rare event search collaborations contributed to this initiative via talks and discussions. The contributing collaborations were CONNIE, CRESST, DAMIC, EDELWEISS, MINER, NEWS-G, NUCLEUS, RICOCHET, SENSEI and SuperCDMS. They presented data about their observed energy spectra and known backgrounds together with details about the respective measurements. In this paper, we summarize the presented information and give a comprehensive overview of the similarities and differences between the distinct measurements. The provided data is furthermore publicly available on the workshop’s data repository together with a plotting tool for visualization.

  36 citations

• The $U$-plane of rank-one 4d $\mathcal{N}=2$ KK theories

  Cyril Closset, Horia Magureanu

  SciPost Phys. 12, 065 (2022) · published 17 February 2022 | Toggle abstract · pdf

  The simplest non-trivial 5d superconformal field theories (SCFT) are the famous rank-one theories with $E_n$ flavour symmetry. We study their $U$-plane, which is the one-dimensional Coulomb branch of the theory on $\mathbb{R}^4 \times S^1$. The total space of the Seiberg-Witten (SW) geometry -- the $E_n$ SW curve fibered over the $U$-plane -- is described as a rational elliptic surface with a singular fiber of type $I_{9-n}$ at infinity. A classification of all possible Coulomb branch configurations, for the $E_n$ theories and their 4d descendants, is given by Persson's classification of rational elliptic surfaces. We show that the global form of the flavour symmetry group is encoded in the Mordell-Weil group of the SW elliptic fibration. We study in detail many special points in parameters space, such as points where the flavour symmetry enhances, and/or where Argyres-Douglas and Minahan-Nemeschansky theories appear. In a number of important instances, including in the massless limit, the $U$-plane is a modular curve, and we use modularity to investigate aspects of the low-energy physics, such as the spectrum of light particles at strong coupling and the associated BPS quivers. We also study the gravitational couplings on the $U$-plane, matching the infrared expectation for the couplings $A(U)$ and $B(U)$ to the UV computation using the Nekrasov partition function.

  36 citations

• Riemannian optimization of isometric tensor networks

  Markus Hauru, Maarten Van Damme, Jutho Haegeman

  SciPost Phys. 10, 040 (2021) · published 17 February 2021 | Toggle abstract · pdf

  Several tensor networks are built of isometric tensors, i.e. tensors satisfying $W^\dagger W = \mathrm{I}$. Prominent examples include matrix product states (MPS) in canonical form, the multiscale entanglement renormalization ansatz (MERA), and quantum circuits in general, such as those needed in state preparation and quantum variational eigensolvers. We show how gradient-based optimization methods on Riemannian manifolds can be used to optimize tensor networks of isometries to represent e.g. ground states of 1D quantum Hamiltonians. We discuss the geometry of Grassmann and Stiefel manifolds, the Riemannian manifolds of isometric tensors, and review how state-of-the-art optimization methods like nonlinear conjugate gradient and quasi-Newton algorithms can be implemented in this context. We apply these methods in the context of infinite MPS and MERA, and show benchmark results in which they outperform the best previously-known optimization methods, which are tailor-made for those specific variational classes. We also provide open-source implementations of our algorithms.

  35 citations

• The ALF (Algorithms for Lattice Fermions) project release 2.0. Documentation for the auxiliary-field quantum Monte Carlo code

  F. F. Assaad, M. Bercx, F. Goth, A. Götz, J. S. Hofmann, E. Huffman, Z. Liu, F. Parisen Toldin, J. S. E. Portela, J. Schwab

  SciPost Phys. Codebases 1 (2022) · published 22 August 2022 · licensed under CC BY-SA (4.0) | Toggle abstract · pdf

  The Algorithms for Lattice Fermions package provides a general code for the finite-temperature and projective auxiliary-field quantum Monte Carlo algorithm. The code is engineered to be able to simulate any model that can be written in terms of sums of single-body operators, of squares of single-body operators and single-body operators coupled to a bosonic field with given dynamics. The package includes five pre-defined model classes: SU(N) Kondo, SU(N) Hubbard, SU(N) t-V and SU(N) models with long range Coulomb repulsion on honeycomb, square and N-leg lattices, as well as $Z_2$ unconstrained lattice gauge theories coupled to fermionic and $Z_2$ matter. An implementation of the stochastic Maximum Entropy method is also provided. One can download the code from our Git instance at https://git.physik.uni-wuerzburg.de/ALF/ALF/-/tree/ALF-2.0 and sign in to file issues.

  35 citations

• Investigation of the Néel phase of the frustrated Heisenberg antiferromagnet by differentiable symmetric tensor networks

  Juraj Hasik, Didier Poilblanc, Federico Becca

  SciPost Phys. 10, 012 (2021) · published 20 January 2021 | Toggle abstract · pdf

  The recent progress in the optimization of two-dimensional tensor networks [H.-J. Liao, J.-G. Liu, L. Wang, and T. Xiang, Phys. Rev. X 9, 031041 (2019)] based on automatic differentiation opened the way towards precise and fast optimization of such states and, in particular, infinite projected entangled-pair states (iPEPS) that constitute a generic-purpose Ansatz for lattice problems governed by local Hamiltonians. In this work, we perform an extensive study of a paradigmatic model of frustrated magnetism, the J 1 − J 2 Heisenberg an- tiferromagnet on the square lattice. By using advances in both optimization and subsequent data analysis, through finite correlation-length scaling, we re- port accurate estimations of the magnetization curve in the Néel phase for J 2 /J 1 ≤ 0.45. The unrestricted iPEPS simulations reveal an U (1) symmetric structure, which we identify and impose on tensors, resulting in a clean and consistent picture of antiferromagnetic order vanishing at the phase transition with a quantum paramagnet at J 2 /J 1 ≈ 0.46(1). The present methodology can be extended beyond this model to study generic order-to-disorder transitions in magnetic systems.

  35 citations

• Neutrino experiments probe hadrophilic light dark matter

  Yohei Ema, Filippo Sala, Ryosuke Sato

  SciPost Phys. 10, 072 (2021) · published 24 March 2021 | Toggle abstract · pdf

  We use Super-K data to place new strong limits on interactions of sub-GeV Dark Matter (DM) with nuclei, that rely on the DM flux inevitably induced by cosmic-ray upscatterings. We derive analogous sensitivities at Hyper-K and DUNE and compare them with others, e.g. at JUNO. Using simplified models, we find that our proposal tests genuinely new parameter space, allowed both by theoretical consistency and by other direct detection experiments, cosmology, meson decays and our recast of monojet. Our results thus motivate and shape a new physics case for any large volume detector sensitive to nuclear recoils.

  35 citations

• Relative entropy in scattering and the S-matrix bootstrap

  Anjishnu Bose, Parthiv Haldar, Aninda Sinha, Pritish Sinha, Shaswat S Tiwari

  SciPost Phys. 9, 081 (2020) · published 24 November 2020 | Toggle abstract · pdf

  We consider entanglement measures in 2-2 scattering in quantum field theories, focusing on relative entropy which distinguishes two different density matrices. Relative entropy is investigated in several cases which include $\phi^4$ theory, chiral perturbation theory ($\chi PT$) describing pion scattering and dilaton scattering in type II superstring theory. We derive a high energy bound on the relative entropy using known bounds on the elastic differential cross-sections in massive QFTs. In $\chi PT$, relative entropy close to threshold has simple expressions in terms of ratios of scattering lengths. Definite sign properties are found for the relative entropy which are over and above the usual positivity of relative entropy in certain cases. We then turn to the recent numerical investigations of the S-matrix bootstrap in the context of pion scattering. By imposing these sign constraints and the $\rho$ resonance, we find restrictions on the allowed S-matrices. By performing hypothesis testing using relative entropy, we isolate two sets of S-matrices living on the boundary which give scattering lengths comparable to experiments but one of which is far from the 1-loop $\chi PT$ Adler zeros. We perform a preliminary analysis to constrain the allowed space further, using ideas involving positivity inside the extended Mandelstam region, and elastic unitarity.

  35 citations

• Role of Sb in the superconducting kagome metal CsV$_3$Sb$_5$ revealed by its anisotropic compression

  Alexander A. Tsirlin, Pierre Fertey, Brenden R. Ortiz, Berina Klis, Valentino Merkl, Martin Dressel, Stephen D. Wilson, Ece Uykur

  SciPost Phys. 12, 049 (2022) · published 2 February 2022 | Toggle abstract · pdf

  Pressure evolution of the superconducting kagome metal CsV$_3$Sb$_5$ is studied with single-crystal x-ray diffraction and density-functional band-structure calculations. A highly anisotropic compression observed up to 5 GPa is ascribed to the fast shrinkage of the Cs-Sb distances and suppression of Cs rattling motion. This prevents Sb displacements required to stabilize the three-dimensional charge-density-wave (CDW) order and elucidates the disappearance of the CDW already at 2 GPa despite only minor changes in the electronic structure of the normal state. At higher pressures, vanadium bands still change only marginally, whereas antimony bands undergo a major reconstruction caused by the gradual formation of the interlayer Sb-Sb bonds. Our results exclude pressure tuning of vanadium kagome bands as the main mechanism for the non-trivial evolution of superconductivity in real-world kagome metals. Concurrently, we establish the central role of Sb atoms in the stabilization of a three-dimensional CDW and Fermi surface reconstruction.

  35 citations

• Time dependent variational principle for tree Tensor Networks

  Daniel Bauernfeind, Markus Aichhorn

  SciPost Phys. 8, 024 (2020) · published 7 February 2020 | Toggle abstract · pdf

  We present a generalization of the Time Dependent Variational Principle (TDVP) to any finite sized loop-free tensor network. The major advantage of TDVP is that it can be employed as long as a representation of the Hamiltonian in the same tensor network structure that encodes the state is available. Often, such a representation can be found also for long-range terms in the Hamiltonian. As an application we use TDVP for the Fork Tensor Product States tensor network for multi-orbital Anderson impurity models. We demonstrate that TDVP allows to account for off-diagonal hybridizations in the bath which are relevant when spin-orbit coupling effects are important, or when distortions of the crystal lattice are present.

  35 citations

• Locally quasi-stationary states in noninteracting spin chains

  Maurizio Fagotti

  SciPost Phys. 8, 048 (2020) · published 27 March 2020 | Toggle abstract · pdf

  Locally quasi-stationary states (LQSS) were introduced as inhomogeneous generalisations of stationary states in integrable systems. Roughly speaking, LQSSs look like stationary states, but only locally. Despite their key role in hydrodynamic descriptions, an unambiguous definition of LQSSs was not given. By solving the dynamics in inhomogeneous noninteracting spin chains, we identify the set of LQSSs as a subspace that is invariant under time evolution, and we explicitly construct the latter in a generalised XY model. As a by-product, we exhibit an exact generalised hydrodynamic theory (including "quantum corrections").

  35 citations